Molecular Characterization of Rifampicin and/or Isoniazid Resistant mycobacterium Tuberculosis Complex

Abstract

Introduction:The ability to rapidly and accurately detect drug resistance in Mycobacterium tuberculosis complex (MTBC) isolates is critical for the appropriate treatment of patients suffering from TB and the effectiveness ofTB control programs. Geno Type MTBDR plus will allows rapid confirmation of TB through the identification of genetic mutations associated withrifampicin and isoniazid resistance. Therefore, this study provides genetic information of isoniazid and rifampicin drug resistance TB isolates in Nepal. Objectives: To rapidly identify drug resistant TB in cultured specimen through the identification of genetic mutations associated with rifampin and isoniazid resistance in in Mycobacterium tuberculosis complex (MTBC)isolates. Methods: Fluorescence microscopy was performed on 62 suspected tuberculosis specimen followed by their culture on on Lowenstein–Jensenmedium for detection of Mycobacterium tuberculosis. Culture specimens werethen analysed for identification of rifampicin and /or isoniazid resistance using Genotype MTBDR plusassay. Results: Among the drug resistant isolates, MDR (multidrug resistance i.e.resistant to at least isoniazid and rifampicin) isolates were predominant (51%).Among all rifampicin resistant isolates, 61.76%of them had mutations in the530-533 region ofrpoBgene and was the most commonmutation observed as detected by the lack of binding to various wild type probes in the presence of D 516 V and S531 L mutation. More RIF-monoresistant strains (16.66%) had aD516V mutation(MUT1 band) compared to MDR strains (3.5%).Of all IN Hresistant strains96.96% had a mutation in the katGgene and 3.03% had amutation in the inhAgene. All isoniazid resistant strains that have mutation ininh A gene were found to be multidrug resistant. None of the strains had mutations in both thekatGand inhAgenes. S315T1 and S531L were found asthe mostcommon mutation for rifampicin and isoniazid respectively. Conclusions: Geno Type MDTBR plus assay can be effectively used for the detection of mutationsin most commongenes responsible for isoniazid and/orrifampicin resistance. Keywords: TB, Genotype MTBD Rplus, MDR, MTBC.